Group anagrams

Signed-off-by: begeekmyfriend <[email protected]>

049_group_anagrams/Makefile

@@ -0,0 +1,2 @@
+all:
+	gcc -O2 -o test anagrams.c

049_group_anagrams/anagrams.c

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+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include "../uthash.h"
+
+struct str_hash {
+    char *str;
+    int *indexes;
+    int freq;
+    int cap;
+    UT_hash_handle hh;
+};
+
+static struct str_hash *hash_table = NULL;
+
+static void insert_sort(char *s, int len)
+{
+    long i, j;
+    for (i = 1; i < len; i++) {
+        char tmp = s[i];
+        j = i - 1;
+        for (; j >= 0 && s[j] > tmp; j--) {
+            s[j + 1] = s[j];
+        }
+        s[j + 1] = tmp;
+    }
+}
+
+/**
+ ** Return an array of arrays of size *returnSize.
+ ** The sizes of the arrays are returned as *columnSizes array.
+ ** Note: Both returned array and *columnSizes array must be malloced, assume caller calls free().
+ **/
+static char*** groupAnagrams(char** strs, int strsSize, int** columnSizes, int* returnSize) {
+    int i, j, count = 0;
+    struct str_hash *obj, *tmp;
+    char **words = malloc(strsSize * sizeof(char *));
+
+    for (i = 0; i < strsSize; i++) {
+        int len = strlen(strs[i]);
+        words[i] = malloc(len + 1);
+        strcpy(words[i], strs[i]);
+        insert_sort(words[i], len);
+        HASH_FIND_STR(hash_table, words[i], obj);
+        if (obj == NULL) {
+            obj = malloc(sizeof(*obj));
+            obj->str = words[i];
+            obj->freq = 1;
+            obj->cap = 1;
+            obj->indexes = malloc(sizeof(int));
+            obj->indexes[0] = i;
+            HASH_ADD_STR(hash_table, str, obj);
+            count++;
+        } else {
+            if (obj->freq + 1 >= obj->cap) {
+                obj->cap *= 2;
+                obj->indexes = realloc(obj->indexes, obj->cap * sizeof(int));
+            }
+            obj->indexes[obj->freq++] = i;
+        }
+    }
+
+    char ***ret_lists = malloc(count * sizeof(char **));
+    int *column_sizes = malloc(count * sizeof(int));
+
+    i = 0;
+    HASH_ITER(hh, hash_table, obj, tmp) {
+        ret_lists[i] = malloc(obj->freq * sizeof(char *));
+        column_sizes[i] = obj->freq;
+        for (j = 0; j < column_sizes[i]; j++) {
+            ret_lists[i][j] = strs[obj->indexes[j]];
+        }
+        HASH_DEL(hash_table, obj);
+        free(obj);
+        i++;
+    }
+
+    *columnSizes = column_sizes;
+    *returnSize = count;
+    return ret_lists;
+}
+
+int main(int argc, char **argv)
+{
+    int *column_sizes, count, i, j;
+    char ***lists = groupAnagrams(argv + 1, argc - 1, &column_sizes, &count);
+    for (i = 0; i < count; i++) {
+        for (j = 0; j < column_sizes[i]; j++) {
+            printf("%s\n", lists[i][j]);
+        }
+    }
+    return 0;
+}